Neurotransmitter in the cns main brain chemical system

Exploring Neurotransmitters: The Brain's Messengers

what are neurotransmitters?

Neurotransmitters are like tiny carriers, transmitting messages from one neuron to another across synapses.They carry messages from one nerve cell across a space to the next nerve, muscle or gland cell. They hold the power to stimulate, inhibit or modify.

Neurotransmitters transmit signals across a synapse at different locations such as:

• neuromuscular junction
• neuron to neuron
• neuron to target gland

How They Work:

You have billions of nerve cells in your body. Nerve cells are generally made up of three parts:

• A cell body. The cell body is vital to producing neurotransmitters and maintaining the function of the nerve cell.
• An axon. The axon carries the electrical signals along the nerve cell to the axon terminal.
• An axon terminal. This is where the electrical message is changed to a chemical signal using neurotransmitters to communicate with the next group of nerve cells, muscle cells or organs.

Neurotransmitters are located in a part of the neuron called the axon terminal. They’re stored within thin-walled sacs called synaptic vesicles. Each vesicle can contain thousands of neurotransmitter molecules.

As a message or signal travels along a nerve cell, the electrical charge of the signal causes the vesicles of neurotransmitters to fuse with the nerve cell membrane at the very edge of the cell. The neurotransmitters, which now carry the message, are then released from the axon terminal into a fluid-filled space that’s between one nerve cell and the next target cell (another nerve cell, muscle cell or gland).

After binding, the neurotransmitter then triggers a change or action in the target cell, like an electrical signal in another nerve cell, a muscle contraction or the release of hormones from a cell in a gland.

1. Release: It all begins when the pre-synaptic neuron unleashes the neurotransmitter.
2. Journey: The neurotransmitter makes its daring leap across the synaptic gap.
3. Reception: On the other side, post-synaptic neuron receptors eagerly catch the neurotransmitter, sparking an action potential.

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What happens to neurotransmitters after they deliver their message?

• Fade away (a process called diffusion).
• Are reabsorbed and reused by the nerve cell that released it (a process called reuptake).
• Are broken down by enzymes within the synapse so it can’t be recognized or bind to the receptor cell (a process called degradation).

Different types of neurotransmitters:

Types of Neurotransmitters (structural classification):

• Monoamines: dopamine, serotonin, epinephrine, and norepinephrine.
• Amino Acids: Glutamate, GABA, and glycine.
• Peptides: Endorphins, oxytocin, and vasopressin.

What They Do (functional classification):

• Excitatory: These guys amp up the post-synaptic neurons, making action potentials more likely.
• Inhibitory: The calm in the storm, they dial down neuronal excitability to keep things chill, preventing propagation of an action potential.
• Neuromodulators: alter the strength of transmission between pre-synaptic and post-synaptic neurons by controlling the amount of the neurotransmitter released.

Meet the Players!:

• Glutamate: This is the most common excitatory neurotransmitter of your nervous system. It’s the most abundant neurotransmitter in your brain. It plays a key role in cognitive functions like thinking, learning and memory. Imbalances in glutamate levels are associated with Alzheimer’s disease, dementia, Parkinson’s disease and seizures.
• GABA: The most common inhibitory neurotransmitter of your nervous system, particularly in your brain. It regulates brain activity to prevent problems in the areas of anxiety, irritability, concentration, sleep, seizures and depression.
• Acetylcholine: present in both PNS and CNS. Acetylcholine is released by most neurons in your autonomic nervous system regulating heart rate, blood pressure and gut motility. Acetylcholine plays a role in muscle contractions, memory, motivation, sexual desire, sleep and learning. Imbalances in acetylcholine levels are linked with health issues, including Alzheimer’s disease, seizures and muscle spasms.
• Dopamine: Plays a role in your body’s reward system, which includes feeling pleasure, achieving heightened arousal and learning. Dopamine also helps with focus, concentration, memory, sleep, mood and motivation. Diseases associated with dysfunctions of the dopamine system include Parkinson’s disease, schizophrenia, bipolar disease, restless legs syndrome and attention deficit hyperactivity disorder (ADHD). Many highly addictive drugs (cocaine, methamphetamines, amphetamines) act directly on the dopamine system.
• Serotonin: Inhibitory neurotransmitter. Serotonin helps regulate mood, sleep patterns, sexuality, anxiety, appetite and pain. Diseases associated with serotonin imbalance include seasonal affective disorder, anxiety, depression, fibromyalgia and chronic pain. Medications that regulate serotonin and treat these disorders include selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs).

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reference:

• Salvador notes ( Final notes )